**5. Plaque feature of the internal carotid plaques evaluated by optical coherence tomography**

Recently, intravascular optical coherence tomography (OCT) provides high-resolution, crosssectional images of tissue in situ and has an axial resolution of 10 µm and a lateral resolution of 20 µm [17, 18]. The OCT images of human coronary atherosclerotic plaques obtained in vivo provide additional, more detailed structural information than intravascular ultrasound [19].

factor for stenting. To confirm the presence of intraluminal thrombus, the stenotic site was imaged with OCT (Image Wire, Light-lab imaging, Goodman, Co, Ltd, Nagoya, Japan) using an automatic pull-back device from the distal portion at 1 mm/s. OCT clearly revealed an intraluminal thrombus (Figure 4-C), and a tear of a fibrous cap with ulceration at the more proximalinternalcarotidartery.Carotidarterystentingwascancelledduetoenlargedthrombus being considered a high risk factor, and carotid endarterectomy was performed the next day. The specimen obtained during endarterectomy showed soft plaque and intraluminal throm‐

Tissue Characterization of Carotid Plaques http://dx.doi.org/10.5772/57155 25

bus which coincided with OCT findings performed preoperatively (Figure 4-E, F).

**integrated backscatter ultrasound**

**6. Assessment of arterial medial characteristics in carotid arteries using**

In general, atherosclerotic changes consist of two components: atherosis and sclerosis. According to a pathological study, these changes are recognized as thickening of intima-media thickness (IMT) which is associated with structural atheromatous changes and decreased

**Figure 5.** Representative histological images of carotid media. (A) (C) Histological images stained by elastic van Gieson staining. (B) (D) Digitized images, in which elastic fibers were selected by the following thresholding of the digital im‐ age LUZEX F (Nireco, Kyoto, Japan). (B) Elastic fiber index: 59.3 %, Elastic fragmentation index: 57.7 % and IBS value:

9.1 dB. (D) Elastic fiber index: 18.9 %, Elastic fragmentation index: 79.3 % and IBS value: 14.4 dB.

By applying this technique to carotid plaques, we previously reported the first case of cere‐ bral infarction due to plaque rupture that could be visualized by OCT in the internal carotid artery [20]. An 83-year old male was admitted to our hospital due to newly developed motor weakness of the left hand. MRI-DWI showed multiple high intensity spots in the territory of the middle cerebral artery, and an initial MRA revealed significant stenosis at the origin of the rightinternal carotidartery.Afterangiography,a9-Fguidingcatheterwithanocclusionballoon was navigated to the right common carotid artery and a guidewire with an occlusion balloon (Guardwire, Medtronic Japan Co., Ltd., Tokyo, Japan) was introduced into the external carotid artery. Carotid angiography revealed apparent changes of the wall morphology of the stenotic site, suggesting an enlargement of intraluminal thrombus (Figure 4), which is considered a risk

**Figure 4.** Optical coherence tomography of the internal carotid artery and pathological findings. A: An initial magnet‐ ic resonance angiography revealed severe stenosis of the internal carotid artery and high intensity plaque. B: The caro‐ tid angiogram showed internal carotid artery stenosis and enlargement of an intraluminal protrusion in the internal carotid artery. C: Cross-sections by the optical coherence tomography (OCT) demonstrated intraluminal thrombus with shadowing in the internal carotid artery. D: Cross-sections by intravascular ultrasound showed only eccentric and low-echoic plaque in the internal carotid artery. E: Macroscopic view of surgical specimen revealed intraluminal thrombus formed at the ruptured site of the soft plaque. F: Pathological analysis with Hematoxylin-Eosin staining con‐ firmed soft plaque and intraluminal red thrombus which coincided with OCT findings.

factor for stenting. To confirm the presence of intraluminal thrombus, the stenotic site was imaged with OCT (Image Wire, Light-lab imaging, Goodman, Co, Ltd, Nagoya, Japan) using an automatic pull-back device from the distal portion at 1 mm/s. OCT clearly revealed an intraluminal thrombus (Figure 4-C), and a tear of a fibrous cap with ulceration at the more proximalinternalcarotidartery.Carotidarterystentingwascancelledduetoenlargedthrombus being considered a high risk factor, and carotid endarterectomy was performed the next day. The specimen obtained during endarterectomy showed soft plaque and intraluminal throm‐ bus which coincided with OCT findings performed preoperatively (Figure 4-E, F).

**5. Plaque feature of the internal carotid plaques evaluated by optical**

Recently, intravascular optical coherence tomography (OCT) provides high-resolution, crosssectional images of tissue in situ and has an axial resolution of 10 µm and a lateral resolution of 20 µm [17, 18]. The OCT images of human coronary atherosclerotic plaques obtained in vivo provide additional, more detailed structural information than intravascular ultrasound [19]. By applying this technique to carotid plaques, we previously reported the first case of cere‐ bral infarction due to plaque rupture that could be visualized by OCT in the internal carotid artery [20]. An 83-year old male was admitted to our hospital due to newly developed motor weakness of the left hand. MRI-DWI showed multiple high intensity spots in the territory of the middle cerebral artery, and an initial MRA revealed significant stenosis at the origin of the rightinternal carotidartery.Afterangiography,a9-Fguidingcatheterwithanocclusionballoon was navigated to the right common carotid artery and a guidewire with an occlusion balloon (Guardwire, Medtronic Japan Co., Ltd., Tokyo, Japan) was introduced into the external carotid artery. Carotid angiography revealed apparent changes of the wall morphology of the stenotic site, suggesting an enlargement of intraluminal thrombus (Figure 4), which is considered a risk

**Figure 4.** Optical coherence tomography of the internal carotid artery and pathological findings. A: An initial magnet‐ ic resonance angiography revealed severe stenosis of the internal carotid artery and high intensity plaque. B: The caro‐ tid angiogram showed internal carotid artery stenosis and enlargement of an intraluminal protrusion in the internal carotid artery. C: Cross-sections by the optical coherence tomography (OCT) demonstrated intraluminal thrombus with shadowing in the internal carotid artery. D: Cross-sections by intravascular ultrasound showed only eccentric and low-echoic plaque in the internal carotid artery. E: Macroscopic view of surgical specimen revealed intraluminal thrombus formed at the ruptured site of the soft plaque. F: Pathological analysis with Hematoxylin-Eosin staining con‐

firmed soft plaque and intraluminal red thrombus which coincided with OCT findings.

**coherence tomography**

24 Carotid Artery Disease - From Bench to Bedside and Beyond
